package main

import (
	"fmt"
)

/*
On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed).
Once you pay the cost, you can either climb one or two steps. You need to find minimum cost to reach the top of the
floor, and you can either start from the step with index 0, or the step with index 1.

Example 1:
Input: cost = [10, 15, 20]
Output: 15
Explanation: Cheapest is start on cost[1], pay that cost and go to the top.
Example 2:
Input: cost = [1, 100, 1, 1, 1, 100, 1, 1, 100, 1]
Output: 6
Explanation: Cheapest is start on cost[0], and only step on 1s, skipping cost[3].

Note:
cost will have a length in the range [2, 1000].
Every cost[i] will be an integer in the range [0, 999].
*/

func main() {
	fmt.Println(minCostClimbingStairs([]int{10, 15, 20}))
	fmt.Println(minCostClimbingStairs([]int{1, 100, 1, 1, 1, 100, 1, 1, 100, 1}))
	fmt.Println(minCostClimbingStairs([]int{841, 462, 566, 398, 243, 248, 238, 650, 989, 576, 361, 126, 334, 729, 446, 897, 953, 38, 195, 679, 65, 707, 196, 705, 569, 275, 259, 872, 630, 965, 978, 109, 56, 523, 851, 887, 91, 544, 598, 963, 305, 481, 959, 560, 454, 883, 50, 216, 732, 572, 511, 156, 177, 831, 122, 667, 548, 978, 771, 880, 922, 777, 990, 498, 525, 317, 469, 151, 874, 202, 519, 139, 670, 341, 514, 469, 858, 913, 94, 849, 839, 813, 664, 163, 3, 802, 21, 634, 944, 901, 446, 186, 843, 742, 330, 610, 932, 614, 625, 169, 833, 4, 81, 55, 124, 294, 71, 24, 929, 534, 621, 543, 417, 534, 427, 327, 179, 90, 341, 949, 368, 692, 646, 290, 488, 145, 273, 617, 596, 82, 538, 751, 80, 616, 763, 826, 932, 184, 630, 478, 163, 925, 259, 237, 839, 602, 60, 786, 603, 413, 816, 278, 4, 35, 243, 64, 631, 405, 23, 638, 618, 829, 481, 877, 756, 482, 999, 973, 718, 157, 262, 752, 931, 882, 741, 40, 77, 535, 542, 879, 607, 879, 321, 46, 210, 116, 244, 830, 591, 285, 382, 925, 48, 497, 913, 203, 239, 696, 162, 623, 291, 525, 950, 27, 546, 293, 108, 577, 672, 354, 256, 3, 671, 998, 22, 989, 557, 424, 251, 923, 542, 243, 46, 488, 80, 374, 372, 334, 190, 817, 150, 742, 362, 196, 75, 193, 162, 645, 859, 758, 433, 903, 199, 289, 175, 303, 475, 818, 213, 576, 181, 668, 243, 297, 572, 549, 840, 161, 292, 719, 226, 338, 981, 345, 203, 655, 210, 65, 111, 746, 76, 935, 406, 646, 976, 567, 32, 726, 638, 674, 727, 861, 426, 297, 349, 464, 973, 341, 452, 826, 223, 805, 940, 458, 468, 967, 107, 345, 987, 553, 407, 916, 103, 324, 367, 864, 74, 946, 712, 596, 105, 194, 79, 634, 855, 703, 70, 170, 543, 208, 739, 632, 663, 880, 857, 824, 258, 743, 488, 659, 647, 470, 958, 492, 211, 927, 356, 488, 744, 570, 143, 674, 502, 589, 270, 80, 6, 463, 506, 556, 495, 713, 407, 229, 689, 280, 162, 454, 757, 565, 267, 575, 417, 948, 607, 269, 852, 938, 560, 24, 222, 580, 604, 800, 628, 487, 485, 615, 796, 384, 555, 226, 412, 445, 503, 810, 949, 966, 28, 768, 83, 213, 883, 963, 831, 390, 951, 378, 497, 440, 780, 209, 734, 290, 96, 398, 146, 56, 445, 880, 910, 858, 671, 164, 552, 686, 748, 738, 837, 556, 710, 787, 343, 137, 298, 685, 909, 828, 499, 816, 538, 604, 652, 7, 272, 729, 529, 343, 443, 593, 992, 434, 588, 936, 261, 873, 64, 177, 827, 172, 712, 628, 609, 328, 672, 376, 628, 441, 9, 92, 525, 222, 654, 699, 134, 506, 934, 178, 270, 770, 994, 158, 653, 199, 833, 802, 553, 399, 366, 818, 523, 447, 420, 957, 669, 267, 118, 535, 971, 180, 469, 768, 184, 321, 712, 167, 867, 12, 660, 283, 813, 498, 192, 740, 696, 421, 504, 795, 894, 724, 562, 234, 110, 88, 100, 408, 104, 864, 473, 59, 474, 922, 759, 720, 69, 490, 540, 962, 461, 324, 453, 91, 173, 870, 470, 292, 394, 771, 161, 777, 287, 560, 532, 339, 301, 90, 411, 387, 59, 67, 828, 775, 882, 677, 9, 393, 128, 910, 630, 396, 77, 321, 642, 568, 817, 222, 902, 680, 596, 359, 639, 189, 436, 648, 825, 46, 699, 967, 202, 954, 680, 251, 455, 420, 599, 20, 894, 224, 47, 266, 644, 943, 808, 653, 563, 351, 709, 116, 849, 38, 870, 852, 333, 829, 306, 881, 203, 660, 266, 540, 510, 748, 840, 821, 199, 250, 253, 279, 672, 472, 707, 921, 582, 713, 900, 137, 70, 912, 51, 250, 188, 967, 14, 608, 30, 541, 424, 813, 343, 297, 346, 27, 774, 549, 931, 141, 81, 120, 342, 288, 332, 967, 768, 178, 230, 378, 800, 408, 272, 596, 560, 942, 612, 910, 743, 461, 425, 878, 254, 929, 780, 641, 657, 279, 160, 184, 585, 651, 204, 353, 454, 536, 185, 550, 428, 125, 889, 436, 906, 99, 942, 355, 666, 746, 964, 936, 661, 515, 978, 492, 836, 468, 867, 422, 879, 92, 438, 802, 276, 805, 832, 649, 572, 638, 43, 971, 974, 804, 66, 100, 792, 878, 469, 585, 254, 630, 309, 172, 361, 906, 628, 219, 534, 617, 95, 190, 541, 93, 477, 933, 328, 984, 117, 678, 746, 296, 232, 240, 532, 643, 901, 982, 342, 918, 884, 62, 68, 835, 173, 493, 252, 382, 862, 672, 803, 803, 873, 24, 431, 580, 257, 457, 519, 388, 218, 970, 691, 287, 486, 274, 942, 184, 817, 405, 575, 369, 591, 713, 158, 264, 826, 870, 561, 450, 419, 606, 925, 710, 758, 151, 533, 405, 946, 285, 86, 346, 685, 153, 834, 625, 745, 925, 281, 805, 99, 891, 122, 102, 874, 491, 64, 277, 277, 840, 657, 443, 492, 880, 925, 65, 880, 393, 504, 736, 340, 64, 330, 318, 703, 949, 950, 887, 956, 39, 595, 764, 176, 371, 215, 601, 435, 249, 86, 761, 793, 201, 54, 189, 451, 179, 849, 760, 689, 539, 453, 450, 404, 852, 709, 313, 529, 666, 545, 399, 808, 290, 848, 129, 352, 846, 2, 266, 777, 286, 22, 898, 81, 299, 786, 949, 435, 434, 695, 298, 402, 532, 177, 399, 458, 528, 672, 882, 90, 547, 690, 935, 424, 516, 390, 346, 702, 781, 644, 794, 420, 116, 24, 919, 467, 543, 58, 938, 217, 502, 169, 457, 723, 122, 158, 188, 109, 868, 311, 708, 8, 893, 853, 376, 359, 223, 654, 895, 877, 709, 940, 195, 323, 64, 51, 807, 510, 170, 508, 155, 724, 784, 603, 67, 316, 217, 148, 972, 19, 658, 5, 762, 618, 744, 534, 956, 703, 434, 302, 541, 997, 214, 429, 961, 648, 774, 244, 684, 218, 49, 729, 990, 521, 948, 317, 847, 76, 566, 415, 874, 399, 613, 816, 613, 467, 191}))
}

var (
	min int
)

func minCostClimbingStairs(cost []int) int {
	//min = math.MaxInt32

	//minCostBT(cost, -1, 0, 0)

	return minCostDP(cost)
	//return min
}

// backtracking(time limit exceeded)
func minCostBT(arr []int, idx, steps, cost int) {
	if idx >= len(arr) {
		if cost < min {
			fmt.Println("min cost", idx, steps, cost)
			min = cost
		}
		return
	}

	if idx == -1 {
		cost = 0
	} else {
		cost += arr[idx]
	}

	minCostBT(arr, idx+1, steps+1, cost)
	minCostBT(arr, idx+2, steps+1, cost)
}

//dynamic programming
func minCostDP(cost []int) int {
	dp0 := cost[0]
	dp1 := cost[1]

	for i := 2; i < len(cost); i++ {
		dp := minCost(dp0+cost[i], dp1+cost[i])
		dp0 = dp1
		dp1 = dp
	}

	return minCost(dp0, dp1)
}

func minCost(cost1, cost2 int) int {
	if cost1 < cost2 {
		return cost1
	}

	return cost2
}
